Audio file incremental reading

dpf.mk

@@ -56,6 +56,7 @@ sfizz-clean:
 
 SFIZZ_SOURCES = \
 	src/sfizz/ADSREnvelope.cpp \
+	src/sfizz/AudioReader.cpp \
 	src/sfizz/Curve.cpp \
 	src/sfizz/effects/Apan.cpp \
 	src/sfizz/Effects.cpp \

src/CMakeLists.txt

@@ -8,6 +8,7 @@ set (SFIZZ_SOURCES
     sfizz/FileId.cpp
     sfizz/FilePool.cpp
     sfizz/FileInstrument.cpp
+    sfizz/AudioReader.cpp
     sfizz/FilterPool.cpp
     sfizz/EQPool.cpp
     sfizz/Region.cpp

src/sfizz/AudioReader.cpp

@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#include "AudioReader.h"
+#include <sndfile.hh>
+#include <algorithm>
+
+namespace sfz {
+
+class BasicSndfileReader : public AudioReader {
+public:
+    explicit BasicSndfileReader(SndfileHandle handle) : handle_(handle) {}
+    virtual ~BasicSndfileReader() {}
+
+    int format() const override;
+    int64_t frames() const override;
+    unsigned channels() const override;
+    unsigned sampleRate() const override;
+    bool getInstrument(SF_INSTRUMENT* instrument) override;
+
+protected:
+    SndfileHandle handle_;
+};
+
+int BasicSndfileReader::format() const
+{
+    return handle_.format();
+}
+
+int64_t BasicSndfileReader::frames() const
+{
+    return handle_.frames();
+}
+
+unsigned BasicSndfileReader::channels() const
+{
+    return handle_.channels();
+}
+
+unsigned BasicSndfileReader::sampleRate() const
+{
+    return handle_.samplerate();
+}
+
+bool BasicSndfileReader::getInstrument(SF_INSTRUMENT* instrument)
+{
+    if (handle_.command(SFC_GET_INSTRUMENT, instrument, sizeof(SF_INSTRUMENT)) == SF_FALSE)
+        return false;
+    return true;
+}
+
+//------------------------------------------------------------------------------
+
+/**
+ * @brief Audio file reader in forward direction
+ */
+class ForwardReader : public BasicSndfileReader {
+public:
+    explicit ForwardReader(SndfileHandle handle);
+    AudioReaderType type() const override;
+    size_t readNextBlock(float* buffer, size_t frames) override;
+};
+
+ForwardReader::ForwardReader(SndfileHandle handle)
+    : BasicSndfileReader(handle)
+{
+}
+
+AudioReaderType ForwardReader::type() const
+{
+    return AudioReaderType::Forward;
+}
+
+size_t ForwardReader::readNextBlock(float* buffer, size_t frames)
+{
+    sf_count_t readFrames = handle_.readf(buffer, frames);
+    if (frames <= 0)
+        return 0;
+
+    return readFrames;
+}
+
+//------------------------------------------------------------------------------
+
+template <size_t N, class T = float>
+struct AudioFrame {
+    T samples[N];
+};
+
+/**
+ * @brief Reorder a sequence of frames in reverse
+ */
+static void reverse_frames(float* data, sf_count_t frames, unsigned channels)
+{
+    switch (channels) {
+
+#define SPECIALIZE_FOR(N)                                           \
+        case N:                                                     \
+            std::reverse(                                           \
+                reinterpret_cast<AudioFrame<N> *>(data),            \
+                reinterpret_cast<AudioFrame<N> *>(data) + frames);  \
+            break
+
+    SPECIALIZE_FOR(1);
+    SPECIALIZE_FOR(2);
+
+    default:
+        for (sf_count_t i = 0; i < frames / 2; ++i) {
+            sf_count_t j = frames - 1 - i;
+            float* frame1 = &data[i * channels];
+            float* frame2 = &data[j * channels];
+            for (unsigned c = 0; c < channels; ++c)
+                std::swap(frame1[c], frame2[c]);
+        }
+        break;
+
+#undef SPECIALIZE_FOR
+    }
+}
+
+//------------------------------------------------------------------------------
+
+/**
+ * @brief Audio file reader in reverse direction, for fast-seeking formats
+ */
+class ReverseReader : public BasicSndfileReader {
+public:
+    explicit ReverseReader(SndfileHandle handle);
+    AudioReaderType type() const override;
+    size_t readNextBlock(float* buffer, size_t frames) override;
+
+private:
+    sf_count_t position_ {};
+};
+
+ReverseReader::ReverseReader(SndfileHandle handle)
+    : BasicSndfileReader(handle)
+{
+    position_ = handle.seek(0, SF_SEEK_END);
+}
+
+AudioReaderType ReverseReader::type() const
+{
+    return AudioReaderType::Reverse;
+}
+
+size_t ReverseReader::readNextBlock(float* buffer, size_t frames)
+{
+    sf_count_t position = position_;
+    const unsigned channels = handle_.channels();
+
+    const sf_count_t readFrames = std::min<sf_count_t>(frames, position);
+    if (readFrames <= 0)
+        return false;
+
+    position -= readFrames;
+    if (handle_.seek(position, SEEK_SET) != position ||
+        handle_.readf(buffer, readFrames) != readFrames)
+        return false;
+
+    position_ = position;
+    reverse_frames(buffer, readFrames, channels);
+    return readFrames;
+}
+
+//------------------------------------------------------------------------------
+
+/**
+ * @brief Audio file reader in reverse direction, for slow-seeking formats
+ */
+class NoSeekReverseReader : public BasicSndfileReader {
+public:
+    explicit NoSeekReverseReader(SndfileHandle handle);
+    AudioReaderType type() const override;
+    size_t readNextBlock(float* buffer, size_t frames) override;
+
+private:
+    void readWholeFile();
+
+private:
+    std::unique_ptr<float[]> fileBuffer_;
+    sf_count_t fileFramesLeft_ { 0 };
+};
+
+NoSeekReverseReader::NoSeekReverseReader(SndfileHandle handle)
+    : BasicSndfileReader(handle)
+{
+}
+
+AudioReaderType NoSeekReverseReader::type() const
+{
+    return AudioReaderType::NoSeekReverse;
+}
+
+size_t NoSeekReverseReader::readNextBlock(float* buffer, size_t frames)
+{
+    float* fileBuffer = fileBuffer_.get();
+    if (!fileBuffer) {
+        readWholeFile();
+        fileBuffer = fileBuffer_.get();
+    }
+
+    const unsigned channels = handle_.channels();
+    const sf_count_t fileFramesLeft = fileFramesLeft_;
+    sf_count_t readFrames = std::min<sf_count_t>(frames, fileFramesLeft);
+    if (readFrames <= 0)
+        return 0;
+
+    std::copy(
+        &fileBuffer[channels * (fileFramesLeft - readFrames)],
+        &fileBuffer[channels * fileFramesLeft], buffer);
+    reverse_frames(buffer, readFrames, channels);
+
+    fileFramesLeft_ = fileFramesLeft - readFrames;
+    return readFrames;
+}
+
+void NoSeekReverseReader::readWholeFile()
+{
+    const sf_count_t frames = handle_.frames();
+    const unsigned channels = handle_.channels();
+    float* fileBuffer = new float[channels * frames];
+    fileBuffer_.reset(fileBuffer);
+    fileFramesLeft_ = handle_.readf(fileBuffer, frames);
+}
+
+//------------------------------------------------------------------------------
+
+const std::error_category& sndfile_category()
+{
+    class sndfile_category : public std::error_category {
+    public:
+        const char* name() const noexcept override
+        {
+            return "sndfile";
+        }
+
+        std::string message(int condition) const override
+        {
+            const char* str = sf_error_number(condition);
+            return str ? str : "";
+        }
+    };
+
+    static const sndfile_category cat;
+    return cat;
+}
+
+//------------------------------------------------------------------------------
+
+class DummyAudioReader : public AudioReader {
+public:
+    explicit DummyAudioReader(AudioReaderType type) : type_(type) {}
+    AudioReaderType type() const override { return type_; }
+    int format() const override { return 0; }
+    int64_t frames() const override { return 0; }
+    unsigned channels() const override { return 1; }
+    unsigned sampleRate() const override { return 44100; }
+    size_t readNextBlock(float*, size_t) override { return 0; }
+    bool getInstrument(SF_INSTRUMENT* ) override { return false; }
+
+private:
+    AudioReaderType type_ {};
+};
+
+//------------------------------------------------------------------------------
+
+static bool formatHasFastSeeking(int format)
+{
+    bool fast;
+
+    const int type = format & SF_FORMAT_TYPEMASK;
+    const int subtype = format & SF_FORMAT_SUBMASK;
+
+    switch (type) {
+    case SF_FORMAT_WAV:
+    case SF_FORMAT_AIFF:
+    case SF_FORMAT_AU:
+    case SF_FORMAT_RAW:
+    case SF_FORMAT_WAVEX:
+        // TODO: list more PCM formats that support fast seeking
+        fast = subtype >= SF_FORMAT_PCM_S8 && subtype <= SF_FORMAT_DOUBLE;
+        break;
+    case SF_FORMAT_FLAC:
+        // seeking has acceptable overhead
+        fast = true;
+        break;
+    case SF_FORMAT_OGG:
+        // ogg is prohibitively slow at seeking (possibly others)
+        // cf. https://github.com/erikd/libsndfile/issues/491
+        fast = false;
+        break;
+    default:
+        fast = false;
+        break;
+    }
+
+    return fast;
+}
+
+AudioReaderPtr createAudioReader(const fs::path& path, bool reverse, std::error_code* ec)
+{
+    AudioReaderPtr reader;
+
+    if (ec)
+        ec->clear();
+
+#if defined(_WIN32)
+    SndfileHandle handle(path.wstring().c_str());
+#else
+    SndfileHandle handle(path.c_str());
+#endif
+
+    if (!handle) {
+        if (ec)
+            *ec = std::error_code(handle.error(), sndfile_category());
+        reader.reset(new DummyAudioReader(reverse ? AudioReaderType::Reverse : AudioReaderType::Forward));
+    }
+    else if (!reverse)
+        reader.reset(new ForwardReader(handle));
+    else if (formatHasFastSeeking(handle.format()))
+        reader.reset(new ReverseReader(handle));
+    else
+        reader.reset(new NoSeekReverseReader(handle));
+
+    return reader;
+}
+
+AudioReaderPtr createExplicitAudioReader(const fs::path& path, AudioReaderType type, std::error_code* ec)
+{
+    AudioReaderPtr reader;
+
+    if (ec)
+        ec->clear();
+
+#if defined(_WIN32)
+    SndfileHandle handle(path.wstring().c_str());
+#else
+    SndfileHandle handle(path.c_str());
+#endif
+
+    if (!handle) {
+        if (ec)
+            *ec = std::error_code(handle.error(), sndfile_category());
+        reader.reset(new DummyAudioReader(type));
+    }
+    else {
+        switch (type) {
+        case AudioReaderType::Forward:
+            reader.reset(new ForwardReader(handle));
+            break;
+        case AudioReaderType::Reverse:
+            reader.reset(new ReverseReader(handle));
+            break;
+        case AudioReaderType::NoSeekReverse:
+            reader.reset(new NoSeekReverseReader(handle));
+            break;
+        }
+    }
+
+    return reader;
+}
+
+} // namespace sfz

src/sfizz/AudioReader.h

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+#pragma once
+#include "absl/types/span.h"
+#include "ghc/fs_std.hpp"
+#include <system_error>
+#include <memory>
+#if defined(_WIN32)
+#define ENABLE_SNDFILE_WINDOWS_PROTOTYPES 1
+#include <windows.h>
+#endif
+#include <sndfile.h>
+
+namespace sfz {
+
+/**
+ * @brief Designation of a particular kind of audio reader
+ */
+enum class AudioReaderType {
+    //! Reader in forward direction
+    Forward,
+    //! Reader in reverse direction
+    Reverse,
+    //! Reader in reverse direction, operating on a whole file instead of seeking
+    NoSeekReverse,
+};
+
+/**
+ * @brief Reader of audio file data
+ */
+class AudioReader {
+public:
+    virtual ~AudioReader() {}
+    virtual AudioReaderType type() const = 0;
+    virtual int format() const = 0;
+    virtual int64_t frames() const = 0;
+    virtual unsigned channels() const = 0;
+    virtual unsigned sampleRate() const = 0;
+    virtual size_t readNextBlock(float* buffer, size_t frames) = 0;
+    virtual bool getInstrument(SF_INSTRUMENT* instrument) = 0;
+};
+
+typedef std::unique_ptr<AudioReader> AudioReaderPtr;
+
+/**
+ * @brief Create a file reader of detected type.
+ */
+AudioReaderPtr createAudioReader(const fs::path& path, bool reverse, std::error_code* ec = nullptr);
+
+/**
+ * @brief Create a file reader of explicit type. (for testing purposes)
+ */
+AudioReaderPtr createExplicitAudioReader(const fs::path& path, AudioReaderType type, std::error_code* ec = nullptr);
+
+} // namespace sfz

src/sfizz/FilePool.cpp

@@ -24,6 +24,7 @@
 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "FilePool.h"
+#include "AudioReader.h"
 #include "FileInstrument.h"
 #include "Buffer.h"
 #include "AudioBuffer.h"
@@ -40,69 +41,50 @@
 #include <sndfile.hh>
 #include <thread>
 
-void readBaseFile(SndfileHandle& sndFile, sfz::FileAudioBuffer& output, uint32_t numFrames, bool reverse)
+void readBaseFile(sfz::AudioReader& reader, sfz::FileAudioBuffer& output, uint32_t numFrames)
 {
     output.reset();
     output.resize(numFrames);
 
-    if (reverse)
-        sndFile.seek(-static_cast<sf_count_t>(numFrames), SEEK_END);
-
-    const unsigned channels = sndFile.channels();
+    const unsigned channels = reader.channels();
 
     if (channels == 1) {
         output.addChannel();
         output.clear();
-        sndFile.readf(output.channelWriter(0), numFrames);
+        reader.readNextBlock(output.channelWriter(0), numFrames);
     } else if (channels == 2) {
         output.addChannel();
         output.addChannel();
         output.clear();
         sfz::Buffer<float> tempReadBuffer { 2 * numFrames };
-        sndFile.readf(tempReadBuffer.data(), numFrames);
+        reader.readNextBlock(tempReadBuffer.data(), numFrames);
         sfz::readInterleaved(tempReadBuffer, output.getSpan(0), output.getSpan(1));
     }
-
-    if (reverse) {
-        for (unsigned c = 0; c < channels; ++c) {
-            // TODO: consider optimizing with SIMD
-            absl::Span<float> channel = output.getSpan(c);
-            std::reverse(channel.begin(), channel.end());
-        }
-    }
 }
 
-std::unique_ptr<sfz::FileAudioBuffer> readFromFile(SndfileHandle& sndFile, uint32_t numFrames, sfz::Oversampling factor, bool reverse)
+std::unique_ptr<sfz::FileAudioBuffer> readFromFile(sfz::AudioReader& reader, uint32_t numFrames, sfz::Oversampling factor)
 {
     auto baseBuffer = absl::make_unique<sfz::FileAudioBuffer>();
-    readBaseFile(sndFile, *baseBuffer, numFrames, reverse);
+    readBaseFile(reader, *baseBuffer, numFrames);
 
     if (factor == sfz::Oversampling::x1)
         return baseBuffer;
 
-    auto outputBuffer = absl::make_unique<sfz::FileAudioBuffer>(sndFile.channels(), numFrames * static_cast<int>(factor));
+    auto outputBuffer = absl::make_unique<sfz::FileAudioBuffer>(reader.channels(), numFrames * static_cast<int>(factor));
     outputBuffer->clear();
     sfz::Oversampler oversampler { factor };
     oversampler.stream(*baseBuffer, *outputBuffer);
     return outputBuffer;
 }
 
-void streamFromFile(SndfileHandle& sndFile, uint32_t numFrames, sfz::Oversampling factor, bool reverse, sfz::FileAudioBuffer& output, std::atomic<size_t>* filledFrames = nullptr)
+void streamFromFile(sfz::AudioReader& reader, uint32_t numFrames, sfz::Oversampling factor, sfz::FileAudioBuffer& output, std::atomic<size_t>* filledFrames = nullptr)
 {
-    if (factor == sfz::Oversampling::x1) {
-        readBaseFile(sndFile, output, numFrames, reverse);
-        if (filledFrames != nullptr)
-            filledFrames->store(numFrames);
-        return;
-    }
-
-    auto baseBuffer = readFromFile(sndFile, numFrames, sfz::Oversampling::x1, reverse);
     output.reset();
-    output.addChannels(baseBuffer->getNumChannels());
+    output.addChannels(reader.channels());
     output.resize(numFrames * static_cast<int>(factor));
     output.clear();
     sfz::Oversampler oversampler { factor };
-    oversampler.stream(*baseBuffer, output, filledFrames);
+    oversampler.stream(reader, output, filledFrames);
 }
 
 sfz::FilePool::FilePool(sfz::Logger& logger)
@@ -210,24 +192,26 @@ absl::optional<sfz::FileInformation> sfz::FilePool::getFileInformation(const Fil
     if (!fs::exists(file))
         return {};
 
-    SndfileHandle sndFile(file.string().c_str());
-    if (sndFile.channels() != 1 && sndFile.channels() != 2) {
+    AudioReaderPtr reader = createAudioReader(file, fileId.isReverse());
+    const unsigned channels = reader->channels();
+
+    if (channels != 1 && channels != 2) {
         DBG("[sfizz] Missing logic for " << sndFile.channels() << " channels, discarding sample " << fileId);
         return {};
     }
 
     FileInformation returnedValue;
-    returnedValue.end = static_cast<uint32_t>(sndFile.frames()) - 1;
-    returnedValue.sampleRate = static_cast<double>(sndFile.samplerate());
-    returnedValue.numChannels = sndFile.channels();
+    returnedValue.end = static_cast<uint32_t>(reader->frames()) - 1;
+    returnedValue.sampleRate = static_cast<double>(reader->sampleRate());
+    returnedValue.numChannels = reader->channels();
 
     SF_INSTRUMENT instrumentInfo {};
 
-    const int sndFormat = sndFile.format();
+    const int sndFormat = reader->format();
     if ((sndFormat & SF_FORMAT_TYPEMASK) == SF_FORMAT_FLAC)
         sfz::FileInstruments::extractFromFlac(file, instrumentInfo);
     else
-        sndFile.command(SFC_GET_INSTRUMENT, &instrumentInfo, sizeof(instrumentInfo));
+        reader->getInstrument(&instrumentInfo);
 
     if (!fileId.isReverse()) {
         if (instrumentInfo.loop_count > 0) {
@@ -249,10 +233,10 @@ bool sfz::FilePool::preloadFile(const FileId& fileId, uint32_t maxOffset) noexce
         return false;
 
     const fs::path file { rootDirectory / fileId.filename() };
-    SndfileHandle sndFile(file.string().c_str());
+    AudioReaderPtr reader = createAudioReader(file, fileId.isReverse());
 
     // FIXME: Large offsets will require large preloading; is this OK in practice? Apparently sforzando does the same
-    const auto frames = static_cast<uint32_t>(sndFile.frames());
+    const auto frames = static_cast<uint32_t>(reader->frames());
     const auto framesToLoad = [&]() {
         if (preloadSize == 0)
             return frames;
@@ -263,12 +247,12 @@ bool sfz::FilePool::preloadFile(const FileId& fileId, uint32_t maxOffset) noexce
     const auto existingFile = preloadedFiles.find(fileId);
     if (existingFile != preloadedFiles.end()) {
         if (framesToLoad > existingFile->second.preloadedData->getNumFrames()) {
-            preloadedFiles[fileId].preloadedData = readFromFile(sndFile, framesToLoad, oversamplingFactor, fileId.isReverse());
+            preloadedFiles[fileId].preloadedData = readFromFile(*reader, framesToLoad, oversamplingFactor);
         }
     } else {
-        fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(sndFile.samplerate());
+        fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(reader->sampleRate());
         FileDataHandle handle {
-            readFromFile(sndFile, framesToLoad, oversamplingFactor, fileId.isReverse()),
+            readFromFile(*reader, framesToLoad, oversamplingFactor),
             *fileInformation
         };
         preloadedFiles.insert_or_assign(fileId, handle);
@@ -283,17 +267,17 @@ absl::optional<sfz::FileDataHandle> sfz::FilePool::loadFile(const FileId& fileId
         return {};
 
     const fs::path file { rootDirectory / fileId.filename() };
-    SndfileHandle sndFile(file.string().c_str());
+    AudioReaderPtr reader = createAudioReader(file, fileId.isReverse());
 
     // FIXME: Large offsets will require large preloading; is this OK in practice? Apparently sforzando does the same
-    const auto frames = static_cast<uint32_t>(sndFile.frames());
+    const auto frames = static_cast<uint32_t>(reader->frames());
     const auto existingFile = loadedFiles.find(fileId);
     if (existingFile != loadedFiles.end()) {
         return existingFile->second;
     } else {
-        fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(sndFile.samplerate());
+        fileInformation->sampleRate = static_cast<float>(oversamplingFactor) * static_cast<float>(reader->sampleRate());
         FileDataHandle handle {
-            readFromFile(sndFile, frames, oversamplingFactor, fileId.isReverse()),
+            readFromFile(*reader, frames, oversamplingFactor),
             *fileInformation
         };
         loadedFiles.insert_or_assign(fileId, handle);
@@ -342,8 +326,8 @@ void sfz::FilePool::setPreloadSize(uint32_t preloadSize) noexcept
         const auto numFrames = preloadedFile.second.preloadedData->getNumFrames() / static_cast<int>(oversamplingFactor);
         const auto maxOffset = numFrames > this->preloadSize ? static_cast<uint32_t>(numFrames) - this->preloadSize : 0;
         fs::path file { rootDirectory / preloadedFile.first.filename() };
-        SndfileHandle sndFile(file.string().c_str());
-        preloadedFile.second.preloadedData = readFromFile(sndFile, preloadSize + maxOffset, oversamplingFactor, preloadedFile.first.isReverse());
+        AudioReaderPtr reader = createAudioReader(file, preloadedFile.first.isReverse());
+        preloadedFile.second.preloadedData = readFromFile(*reader, preloadSize + maxOffset, oversamplingFactor);
     }
     this->preloadSize = preloadSize;
 }
@@ -392,14 +376,15 @@ void sfz::FilePool::loadingThread() noexcept
         const auto waitDuration = loadStartTime - promise->creationTime;
 
         const fs::path file { rootDirectory / promise->fileId.filename() };
-        SndfileHandle sndFile(file.string().c_str());
-        if (sndFile.error() != 0) {
-            DBG("[sfizz] libsndfile errored for " << promise->fileId << " with message " << sndFile.strError());
+        std::error_code readError;
+        AudioReaderPtr reader = createAudioReader(file, promise->fileId.isReverse(), &readError);
+        if (readError) {
+            DBG("[sfizz] libsndfile errored for " << promise->fileId << " with message " << readError.what());
             promise->dataStatus = FilePromise::DataStatus::Error;
             continue;
         }
-        const auto frames = static_cast<uint32_t>(sndFile.frames());
-        streamFromFile(sndFile, frames, oversamplingFactor, promise->fileId.isReverse(), promise->fileData, &promise->availableFrames);
+        const auto frames = static_cast<uint32_t>(reader->frames());
+        streamFromFile(*reader, frames, oversamplingFactor, promise->fileData, &promise->availableFrames);
         promise->dataStatus = FilePromise::DataStatus::Ready;
         const auto loadDuration = std::chrono::high_resolution_clock::now() - loadStartTime;
         logger.logFileTime(waitDuration, loadDuration, frames, promise->fileId.filename());
@@ -453,8 +438,8 @@ void sfz::FilePool::setOversamplingFactor(sfz::Oversampling factor) noexcept
         const auto numFrames = preloadedFile.second.preloadedData->getNumFrames() / static_cast<int>(this->oversamplingFactor);
         const uint32_t maxOffset = numFrames > this->preloadSize ? static_cast<uint32_t>(numFrames) - this->preloadSize : 0;
         fs::path file { rootDirectory / preloadedFile.first.filename() };
-        SndfileHandle sndFile(file.string().c_str());
-        preloadedFile.second.preloadedData = readFromFile(sndFile, preloadSize + maxOffset, factor, preloadedFile.first.isReverse());
+        AudioReaderPtr reader = createAudioReader(file, preloadedFile.first.isReverse());
+        preloadedFile.second.preloadedData = readFromFile(*reader, preloadSize + maxOffset, factor);
         preloadedFile.second.information.sampleRate *= samplerateChange;
     }
 

src/sfizz/Oversampler.cpp

@@ -7,6 +7,7 @@
 #include "Oversampler.h"
 #include "Buffer.h"
 #include "AudioSpan.h"
+#include "AudioReader.h"
 #include "SIMDConfig.h"
 
 constexpr std::array<double, 12> coeffsStage2x {
@@ -69,28 +70,29 @@ void sfz::Oversampler::stream(AudioSpan<float> input, AudioSpan<float> output, s
     const auto numFrames = input.getNumFrames();
     const auto numChannels = input.getNumChannels();
 
-    std::vector<Upsampler2x> upsampler2x (numChannels);
-    std::vector<Upsampler4x> upsampler4x (numChannels);
-    std::vector<Upsampler8x> upsampler8x (numChannels);
+    std::vector<Upsampler2x> upsampler2x;
+    std::vector<Upsampler4x> upsampler4x;
+    std::vector<Upsampler8x> upsampler8x;
 
     switch(factor)
     {
     case Oversampling::x8:
+        upsampler8x.resize(numChannels);
         for (auto& upsampler: upsampler8x)
             upsampler.set_coefs(coeffsStage8x.data());
         // fallthrough
     case Oversampling::x4:
+        upsampler4x.resize(numChannels);
         for (auto& upsampler: upsampler4x)
             upsampler.set_coefs(coeffsStage4x.data());
         // fallthrough
     case Oversampling::x2:
+        upsampler2x.resize(numChannels);
         for (auto& upsampler: upsampler2x)
             upsampler.set_coefs(coeffsStage2x.data());
         break;
     case Oversampling::x1:
-        for (size_t i = 0; i < numChannels; ++i)
-            copy<float>(input.getConstSpan(i), output.getSpan(i).first(numFrames));
-        return;
+        break;
     }
 
     // Intermediate buffers
@@ -109,20 +111,119 @@ void sfz::Oversampler::stream(AudioSpan<float> input, AudioSpan<float> output, s
         for (size_t chanIdx = 0; chanIdx < numChannels; chanIdx++) {
             const auto inputChunk = input.getSpan(chanIdx).subspan(inputFrameCounter, thisChunkSize);
             const auto outputChunk = output.getSpan(chanIdx).subspan(outputFrameCounter, outputChunkSize);
-            if (factor == Oversampling::x2) {
+            switch (factor) {
+            case Oversampling::x1:
+                copy<float>(inputChunk, outputChunk);
+                break;
+            case Oversampling::x2:
                 upsampler2x[chanIdx].process_block(outputChunk.data(), inputChunk.data(), static_cast<long>(thisChunkSize));
-                continue;
-            }
-            if (factor == Oversampling::x4) {
+                break;
+            case Oversampling::x4:
                 upsampler2x[chanIdx].process_block(span1.data(), inputChunk.data(), static_cast<long>(thisChunkSize));
                 upsampler4x[chanIdx].process_block(outputChunk.data(), span1.data(), static_cast<long>(thisChunkSize * 2));
-                continue;
-            }
-            else if (factor == Oversampling::x8) {
+                break;
+            case Oversampling::x8:
                 upsampler2x[chanIdx].process_block(span1.data(), inputChunk.data(), static_cast<long>(thisChunkSize));
                 upsampler4x[chanIdx].process_block(span2.data(), span1.data(), static_cast<long>(thisChunkSize * 2));
                 upsampler8x[chanIdx].process_block(outputChunk.data(), span2.data(), static_cast<long>(thisChunkSize * 4));
-                continue;
+                break;
+            }
+        }
+        inputFrameCounter += thisChunkSize;
+        outputFrameCounter += outputChunkSize;
+
+        if (framesReady != nullptr)
+            framesReady->fetch_add(outputChunkSize);
+    }
+}
+
+void sfz::Oversampler::stream(AudioReader& input, AudioSpan<float> output, std::atomic<size_t>* framesReady)
+{
+    ASSERT(output.getNumFrames() >= input.getNumFrames() * static_cast<int>(factor));
+    ASSERT(output.getNumChannels() == input.getNumChannels());
+
+    const auto numFrames = static_cast<size_t>(input.frames());
+    const auto numChannels = input.channels();
+
+    std::vector<Upsampler2x> upsampler2x;
+    std::vector<Upsampler4x> upsampler4x;
+    std::vector<Upsampler8x> upsampler8x;
+
+    switch(factor)
+    {
+    case Oversampling::x8:
+        upsampler8x.resize(numChannels);
+        for (auto& upsampler: upsampler8x)
+            upsampler.set_coefs(coeffsStage8x.data());
+        // fallthrough
+    case Oversampling::x4:
+        upsampler4x.resize(numChannels);
+        for (auto& upsampler: upsampler4x)
+            upsampler.set_coefs(coeffsStage4x.data());
+        // fallthrough
+    case Oversampling::x2:
+        upsampler2x.resize(numChannels);
+        for (auto& upsampler: upsampler2x)
+            upsampler.set_coefs(coeffsStage2x.data());
+        break;
+    case Oversampling::x1:
+        break;
+    }
+
+    // Intermediate buffers
+    sfz::Buffer<float> fileBlock { chunkSize * numChannels };
+    sfz::Buffer<float> buffer1 { chunkSize * 2 };
+    sfz::Buffer<float> buffer2 { chunkSize * 4 };
+    auto span1 = absl::MakeSpan(buffer1);
+    auto span2 = absl::MakeSpan(buffer2);
+
+    auto upsample2xFromInterleaved = [numChannels](
+        Upsampler2x& upsampler, float* output, const float* input,
+        size_t numInputFrames, unsigned chanIdx)
+    {
+        for (size_t i = 0; i < numInputFrames; ++i) {
+            float* outp = &output[2 * i];
+            const float* inp = &input[i * numChannels + chanIdx];
+            upsampler.process_sample(outp[0], outp[1], inp[0]);
+        }
+    };
+
+    size_t inputFrameCounter { 0 };
+    size_t outputFrameCounter { 0 };
+    bool inputEof = false;
+    while (!inputEof && inputFrameCounter < numFrames)
+    {
+        // std::cout << "Input frames: " << inputFrameCounter << "/" << numFrames << '\n';
+        auto thisChunkSize = std::min(chunkSize, numFrames - inputFrameCounter);
+        const auto numFramesRead = static_cast<size_t>(
+            input.readNextBlock(fileBlock.data(), thisChunkSize));
+        if (numFramesRead == 0)
+            break;
+        if (numFramesRead < thisChunkSize) {
+            inputEof = true;
+            thisChunkSize = numFramesRead;
+        }
+        const auto outputChunkSize = thisChunkSize * static_cast<int>(factor);
+
+        for (size_t chanIdx = 0; chanIdx < numChannels; chanIdx++) {
+            const auto outputChunk = output.getSpan(chanIdx).subspan(outputFrameCounter, outputChunkSize);
+            switch (factor) {
+            case Oversampling::x1:
+                for (size_t i = 0; i < thisChunkSize; ++i)
+                    outputChunk[i] = fileBlock[i * numChannels + chanIdx];
+                break;
+            case Oversampling::x2:
+                upsample2xFromInterleaved(upsampler2x[chanIdx], outputChunk.data(), fileBlock.data(), thisChunkSize, chanIdx);
+                break;
+            case Oversampling::x4:
+                upsample2xFromInterleaved(upsampler2x[chanIdx], span1.data(), fileBlock.data(), thisChunkSize, chanIdx);
+                upsampler4x[chanIdx].process_block(outputChunk.data(), span1.data(), static_cast<long>(thisChunkSize * 2));
+                break;
+            case Oversampling::x8:
+                upsample2xFromInterleaved(upsampler2x[chanIdx], span1.data(), fileBlock.data(), thisChunkSize, chanIdx);
+                upsampler4x[chanIdx].process_block(span2.data(), span1.data(), static_cast<long>(thisChunkSize * 2));
+                upsampler8x[chanIdx].process_block(outputChunk.data(), span2.data(), static_cast<long>(thisChunkSize * 4));
+                break;
             }
         }
         inputFrameCounter += thisChunkSize;
@@ -131,5 +232,4 @@ void sfz::Oversampler::stream(AudioSpan<float> input, AudioSpan<float> output, s
         if (framesReady != nullptr)
             framesReady->fetch_add(outputChunkSize);
     }
-
 }

src/sfizz/Oversampler.h

@@ -15,6 +15,8 @@
 #include "Config.h"
 
 namespace sfz {
+class AudioReader;
+
 /**
  * @brief Wraps the internal oversampler in a single function that takes an
  *        AudioBuffer and oversamples it in another pre-allocated one. The
@@ -41,6 +43,16 @@ public:
      * @param framesReady an atomic counter for the ready frames. If null no signaling is done.
      */
     void stream(AudioSpan<float> input, AudioSpan<float> output, std::atomic<size_t>* framesReady = nullptr);
+    /**
+     * @brief Stream the oversampling of an input AudioReader into an output
+     *        one, possibly signaling the caller along the way of the number of
+     *        frames that are written.
+     *
+     * @param input
+     * @param output
+     * @param framesReady an atomic counter for the ready frames. If null no signaling is done.
+     */
+    void stream(AudioReader& input, AudioSpan<float> output, std::atomic<size_t>* framesReady = nullptr);
 
     Oversampler() = delete;
     Oversampler(const Oversampler&) = delete;